Factors related to myopia can be divided into two groups: 1) hereditary and 2) environmental. Relationship between heredity and likelihood of myopia has been shown in many studies (13, 14). These studies obviously showed the effect of parental myopia on moderate levels of childhood myopia. Today different areas on several chromosomes are known for severe myopia (such like 18p, 12q, 7q36, TGIF) (15-17). Although it seems that two of these chromosomes (18q, 12q) do not have any relationship with childhood myopia (18).